At 11:33 PM 2/24/2000 , you wrote:
>Thanks for the answer and taking the time to give the explanation too,
>good to know. That posting will be saved for later reference.
>So, if I understand the journey of the oil, the pump draws it from the
>pan and pushes it through the filter. From there the oil is moved
>mechanically or by gravity, right ? And oil pressure only applies when
>your talking about the oil in the pan till it is pushed out of the
>filter, right ?
Oil is pumped under pressure until it goes through he bearings, then it
falls back to the pan from gravity. It's like running a water hose, water
will go to the end, then fall down to the ground. Oil pressure is created
by the pump pumping more oil than can flow through the engine at any given
time.
>Okay, and you said, "Once the filter is filled with oil no change in
>pressure or volume would occur." This assumes you have filled the oil to
>the proper dip stick level after running the engine to allow the filter
>to be filled and not just added the X number of quarts per the owners
>manual. Okay, I got that. I'm presuming the oil pump intake is near the
>bottom of the oil pan. Obviously, the pan can hold more oil than the
>filter, so as long as there is enough oil in the system/pan to keep the
>filter full everything will be okay, right ?
mmmm, yeah. Oil in the filter is under pressure when the engine is
running, the pump is pumping more oil than can flow through the
engine. Oil in the pan is like water in a kitchen sink, it's just
there. Yes, the oil pump pickup tube is down near the bottom of the oil
pan, about an inch off the bottom.
>Okay, a few other questions then:
>Too much oil in the system/pan would cause a problem when the oil needs
>to bypass and can't properly recirculate back into the pan ? This would
>create stress on seals ?
Actually too much oil in the pan is very bad. The crankshaft
counterweights actually stick down about a half inch or so into the oil
pan. As the crank spins, if the oil level is too high, it will splash the
oil and will collect around the crank while it's spinning. There are two
problems with that. First, the added weight of the oil swinging around
with the crank adds weight, an unbalanced weight. Second, it aerates the
oil - gets air mixed in with the oil, and makes it foamy and full of air
bubbles. Air doesn't lubricate too well. Remember the bearing clearances
are 1/3rd the thickness of a sheet of paper.
The oil pump bypass is on the output side of the oil pump. When the
pressure in the engine oil system is to high, it opens (basically a valve)
and the oil that is pumped from the pan, is dumped back into the pan. It
will flow even in the valve is submerged, but it's impossible get it
submerged, unless you add a couple gallons of oil to the pan.
Too much oil in the system is impossible. It's limited by the volume of
all the oil galleries, and exiting orifices and clearances.
>Is the oil pump electrical or mechanical ? Do they go bad ? If so, is
>there a way to tell the pump is going out before real damage is done ?
>Is it correct to figure a bigger filter is really of no advantage.
>Thinking more about this it seems to me it could be a disadvantage, in
>that on a real cold days when the truck is first started it will take the
>engine less time to warm the smaller oil filter, making the oil flow
>better, than it would a larger filter. So, the smaller filter gets "free
>flowing" oil running through the system sooner ?
The oil pump is mechanical. Basically two gears loosely meshed with each
other. The oil pump is driven off the distributor. There is a metal shaft
that plugs into the bottom of the distributor and to the pump
itself. Also, on high volume pumps (pumps with a high relief pressure) and
thick oil, can actually twist that shaft like a licorice stick and break
it. Most high volume/high pressure pumps are installed with a beefed up
drive rod (unless the owner wants to learn the hard way), available from
ARP, Milodon, and many others. It's a stress free design with higher
quality steel.
>Thanks again.
No problem. Been there once myself.
Mike
__________________________
mschwall@flash.net
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